The objectives of this proposal are the design, synthesis and evaluation of specific enzyme-generated inhibitors of human placental aromatase. These inhibitors include enzyme-generated irreversible inhibitors (suicide substrates) as well as competitive reversible inhibitors. Specific inhibitors of human placental aromatase should be valuable tools in studying estrogen biosynthesis in this and other tissues. They may also be of value in the study and treatment of estrogen-dependent tumors. Finally, they may be useful for studying the role played by peripheral aromatization of androgen in male endocrinology.